examples: add component for protocol examples network functionality

* Original commit: espressif/esp-idf@22bef90bd3

examples/common_components/protocol_examples_common/include/protocol_examples_common.h

@@ -0,0 +1,59 @@
+/* Common functions for protocol examples, to establish Wi-Fi or Ethernet connection.
+
+   This example code is in the Public Domain (or CC0 licensed, at your option.)
+
+   Unless required by applicable law or agreed to in writing, this
+   software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
+   CONDITIONS OF ANY KIND, either express or implied.
+ */
+
+#pragma once
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include "esp_err.h"
+#include "tcpip_adapter.h"
+
+#ifdef CONFIG_EXAMPLE_CONNECT_ETHERNET
+#define EXAMPLE_INTERFACE TCPIP_ADAPTER_IF_ETH
+#endif
+
+#ifdef CONFIG_EXAMPLE_CONNECT_WIFI
+#define EXAMPLE_INTERFACE TCPIP_ADAPTER_IF_STA
+#endif
+
+/**
+ * @brief Configure Wi-Fi or Ethernet, connect, wait for IP
+ *
+ * This all-in-one helper function is used in protocols examples to
+ * reduce the amount of boilerplate in the example.
+ *
+ * It is not intended to be used in real world applications.
+ * See examples under examples/wifi/getting_started/ and examples/ethernet/
+ * for more complete Wi-Fi or Ethernet initialization code.
+ *
+ * Read "Establishing Wi-Fi or Ethernet Connection" section in
+ * examples/protocols/README.md for more information about this function.
+ *
+ * @return ESP_OK on successful connection
+ */
+esp_err_t example_connect();
+
+/**
+ * Counterpart to example_connect, de-initializes Wi-Fi or Ethernet
+ */
+esp_err_t example_disconnect();
+
+/**
+ * @brief Configure stdin and stdout to use blocking I/O
+ *
+ * This helper function is used in ASIO examples. It wraps installing the
+ * UART driver and configuring VFS layer to use UART driver for console I/O.
+ */
+esp_err_t example_configure_stdin_stdout();
+
+#ifdef __cplusplus
+}
+#endif